1. Field of the Invention
The present invention relates to an optical disk player, and more specifically to a tracking servo apparatus in an optical disk player.
2. Description of Background Information
In optical disk players, the pickup for reading recording information on a disk-shaped recording medium, such as a video disk or the like (hereinafter, simply referred to as a disk), has an objective lens which converges an irradiation light beam as an information reading spot onto an information recording surface of the disk. An optical system, including the objective lens, is driven in a focusing direction (optical axis direction) by a focusing actuator and in a tracking direction (radial direction of the disk) by a tracking actuator.
In the pickup, when a movable section including the objective lens is driven in the focusing direction, what is called a rolling occurs if a center G of gravity of the movable part is deviated from the optical axis, which, in turn, causes a tracking error. This is equivalent to a tracking error beyond the specification limit of the disk. To prevent such an adverse effect on the tracking servo by the rolling of the pickup which is caused by a mass balance distortion, hitherto, a weight balancer is attached to the pickup body, thereby adjusting the mass balance so as to locate the center G of gravity of the movable section on the optical axis.
However, the method wherein the weight balancer is used has the drawback that use of the weight balancer obstructs the realization of downsizing, lightening of weight, and cost reduction of the pickup. In the pickup in which the downsizing and light weight are realized, there is also a problem such that a space to attach the weight balancer cannot be provided.